The Largest Rat Eradication Ever Attempted, and It Worked

South Georgia is one of the greatest seabird islands on Earth, and for two hundred years its ground-nesting birds — the endemic South Georgia pipit among them — could not breed anywhere rats had reached. The South Georgia Heritage Trust began planning an eradication in 2008 that covered 108,723 hectares, more than eight times larger than any rodent eradication attempted anywhere before, in a place with no roads and weather that grounds aircraft for weeks. Three helicopters spread bait in overlapping swathes across three phases, and in the final phase a team spent six months searching for survivors, three sniffer dogs covering 1,504 miles between them while their handlers walked around a thousand. The island was declared rodent-free on 8 May 2018, and the pipits and pintails that cannot coexist with rats are the measure of it: their return is how the Trust knows.